FIELD OF THE INVENTION
The present invention relates generally to apparatus for automatically providing a measure of the distance between the apparatus and an object. Specifically, the invention relates to the so-called spatial image correlation type or form of such apparatus, wherein the object distance is determined by relatively moving auxiliary image-producing auxiliary optical means and radiation responsive arrays to cause them to occupy a detectable correlation position, this position being a measure of the existing object distance. The invention relates as well to so-called automatic focusing apparatus which utilizes such a distance measure for automatically placing an optical element, such as a camera taking lens, in a focused condition relative to the object for the prevailing object distance.